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This is a blog post, so it should be a regular submission even if you’re the one you wrote it. https://news.ycombinator.com/showhn.html > Show HN is for something you've made that other people can play with. HN users can try it out, give you feedback, and ask questions in the thread.
I too have repurposed a similar machine to try to help me solve a nagging problem. One of my vehicles uses a hydraulic clutch. By design, air bubbles can be trapped in the master cylinder due to factory bends in the lines and the orientation of the master cylinder when it is properly installed. If this happens it will be impossible to shift the gears (manual transmission) until the air is bled from the lines. I tried…
For bleeding hydraulic brakes, which operate on a similar principle, the normal procedure is to open the bleeder valves on the slave cylinders and vigorously pump the pedal, refilling the master as necessary, until the fluid coming out of the bleeders is free of bubbles. Vibrating the lines won't do anything since the air bubbles fill their entire inside diameter.
Bench bleeding involves straightening the lines and orienting the components along the lines, the master cylinder especially, so that air bubbles can flow up thru the lines by gravity and then using a tool to tap the lines and dislodge any bubbles so that they flow up to the fluid reservoir. I decided to hack the process using that back massager to speed up the gravity flow of any trapped air instead of using a screwdriver to tap the lines as they do in the official maintenance procedures. I also left all the parts in the vehicle making access to some curves or bends very difficult. That is why I used the PVC. It allowed me to transfer the vibration to the lines all along the length without removing anything from the vehicle.
I had already tried the usual pumping the clutch and cracking the bleeder valve process and though disappointed, was not surprised to have no success since it usually only works when the air is trapped low in this system inside the clutch slave cylinder near the bleeder valve, not higher up in the section containing the clutch master cylinder.
> the sensor has its own built-in sample rate, 400 times per second. If I read it too quickly, I might just be grabbing the same number twice The author is configuring the sensor wrong i think. The usually way is you setup sampling rate of register, setup fifo inside register, wait for interrupt from sensor(through GPIO pin), then read from FIFO. Just blindly read data from sensor will get you in trouble, like readin…
Anyway, even easier since the OP seems to be dealing a lot with the time between samples, would be to just make sure that at least 2.5 ms have passed before reading the sensor again. Right?
[1] Not sure if older blog posts detail the hardware, I do remember reading about this product on here before.
Mildly related: "Evan and Katelyn" is the name of a youtube channel where (amongst other less mature things) they make a bunch of small things with concrete and epoxy, like a concrete keyboard. Both materials (especially concrete) need some assistance in flowing into small spaces and getting bubbles out. For the size of project they often work on... a personal vibrator seems to work damn well. Concrete keyboard video…
It makes sense. Specific professional tools to vibrate viscous fluids to get bubbles out of it exist (like those odd looking concrete vibrators), but for a small handheld vibrating tool there is already an enormous market of affordable tools which do just that.
> the sensor has its own built-in sample rate, 400 times per second. If I read it too quickly, I might just be grabbing the same number twice The author is configuring the sensor wrong i think. The usually way is you setup sampling rate of register, setup fifo inside register, wait for interrupt from sensor(through GPIO pin), then read from FIFO. Just blindly read data from sensor will get you in trouble, like readin…
Not all microcontrollers[1]} have FIFOs for stuff like this, but perhaps you meant implementing it in software as a regular queue or something. Anyway, even easier since the OP seems to be dealing a lot with the time between samples, would be to just make sure that at least 2.5 ms have passed before reading the sensor again. Right? [1] Not sure if older blog posts detail the hardware, I do remember reading about this…
> would be to just make sure that at least 2.5 ms have passed before reading the sensor again
You're resampling at the same rate by doing this, which won't be accurate due to very slight variations in timings.
[0] https://cdn.shopify.com/s/files/1/0914/0181/4398/files/24-10...
[1] page 19, https://www.st.com/resource/en/datasheet/lis3dh.pdf
Earlier quoted context omitted.
yeah there's all sorts of useful shapes and convenient features, priced for every budget. Better in most ways! pipes just lead to trouble
As I understand it you can even source them with specific bend and taper profiles, which lets you optimize for the geometry of the system you're trying to flush.
Mildly related: "Evan and Katelyn" is the name of a youtube channel where (amongst other less mature things) they make a bunch of small things with concrete and epoxy, like a concrete keyboard. Both materials (especially concrete) need some assistance in flowing into small spaces and getting bubbles out. For the size of project they often work on... a personal vibrator seems to work damn well. Concrete keyboard video…
> the sensor has its own built-in sample rate, 400 times per second. If I read it too quickly, I might just be grabbing the same number twice The author is configuring the sensor wrong i think. The usually way is you setup sampling rate of register, setup fifo inside register, wait for interrupt from sensor(through GPIO pin), then read from FIFO. Just blindly read data from sensor will get you in trouble, like readin…
Not all microcontrollers[1]} have FIFOs for stuff like this, but perhaps you meant implementing it in software as a regular queue or something. Anyway, even easier since the OP seems to be dealing a lot with the time between samples, would be to just make sure that at least 2.5 ms have passed before reading the sensor again. Right? [1] Not sure if older blog posts detail the hardware, I do remember reading about this…
No, i mean the FIFO inside the sensor. The sensor will populate FIFO itself, and trigger interrupt to MCU when the FIFO is full(or half full, configurable)
Mildly related: "Evan and Katelyn" is the name of a youtube channel where (amongst other less mature things) they make a bunch of small things with concrete and epoxy, like a concrete keyboard. Both materials (especially concrete) need some assistance in flowing into small spaces and getting bubbles out. For the size of project they often work on... a personal vibrator seems to work damn well. Concrete keyboard video…
Well, that was a deep rabbit hole.
